Research on protection of a nearly thousand-year-old dilapidated ancient brick pagoda in China

Dilapidated ancient brick pagodas face collapse risks under extreme weather. Using Shanxi’s Ganying Pagoda (second-floor damage and separated bodies) as a case, this study evaluates three reinforcement strategies: steel frame core tube (Case 1), base isolation (Case 2), and their combination (Case 3). Nonlinear dynamic analyses under far-field/near-field seismic waves reveal: Case 1 shortens natural periods, amplifies base shear, and worsens damage under near-field pulses. Case 2 extends periods and controls responses but causes second-floor connection damage due to load transfer between separated bodies. Case 3 integrates isolation and steel frame constraints, maintaining elastic behavior and minimizing damage. Pushover results show Case 1 enhances ultimate capacity, while Cases 2/3 ensure isolator failure precedes structural damage, with Case 3 controlling interstory drifts most effectively. The combined strategy optimally balances structural integrity and heritage preservation.